Not Applicable
Not Applicable
1. Field of the Invention
This invention relates to propellers and particularly boat propellers having auxiliary vanes for improved performance.
2. Description of Related Art
The screw propeller has been in use for well over a century. It enabled steam-powered ships to sail efficiently as compared to the paddle wheel. Despite this improvement, the propeller itself has some problems in producing the best efficiency. A propeller is essentially a set of fan blades that turn in the water. These blades direct water away from the blades in a flame shaped plume, which elongates and increases in efficiency as the speed of the vessel increases. Despite this action, which does propel a ship forward, the propeller blades also throw water from the blades in a tangential pattern extending from the blade edge. Thus, water is thrown outward from the propeller at angles ranging from 0 degrees to 90 degrees. Moreover, the blades even let water fall over the face of the blades, which creates an inefficient back eddy. All water that is not propelled directly perpendicular to the blades reduces the efficiency of the propeller.
One method of improving the efficiency of propellers uses a pipe shroud to encase the propeller. This shroud or nozzle forces more of the water directly out from the propeller. An example of such a system is the Kort nozzle used on large ships. Small boats can also use nozzles, but these often require modification of the motor or boat to accommodate them.
The present invention solves the efficiency problem by producing a propeller that has curved vanes that attach to the blade tips and to the blade body. The use of the curved vanes produces a nozzle effect without the nozzle. The vanes attached to the body of the blade further improve water flow by reducing the tangential flow. Thus, more water is forced directly back from the propeller in the desired direction, which makes the propeller more efficient. Moreover, as noted above, the curved vanes at the blade tips act as a nozzle. However, because the xe2x80x9cnozzlexe2x80x9d is attached to the propeller blades, there is no need to modify the boat motor to accommodate it. In this design, the nozzle turns with the propeller.
A full blade ring or guard can be formed and attached to the blades, if desired. This ring not only enhances to the nozzle effect, it also protect people and items from getting drawn up into the blades of the propeller. This improves propeller safety as well. The propeller blades can have a number of different vane configurations. Moreover, there is a design that allows for variable pitch of the blades.
It is an object of the invention to produce a propeller having curved vanes at the tips of the propeller blades to generate more efficient water flow.
It is another object of the invention to produce a propeller having curved vanes on the body of each propeller blade to generate more efficient water flow.
It is yet another object of the invention to produce a propeller having a combination of curved vanes at the tips of the propeller blades and curved vanes on the body of each propeller blade to generate more efficient water flow.
It is yet another object of the invention to produce a propeller having a combination of curved vanes at the tips of the propeller blades and curved vanes on the body of each propeller blade to generate more efficient water flow and also having a variable pitch element.